In many different environments, content providers want to distribute content to selected recipients by making the content available in multiple content locations. For example, advertisers who distribute their advertisements to advertisement slots want to make use of advertisement slots where the advertisements will be effective in communicating information to potential customers, and when the advertisements will lead to desired activity, such as a purchase of the advertiser's goods or services. In some instances, an advertising campaign for an advertiser can include multiple content locations (e.g., websites). Ads provided by the advertiser can be presented along with content associated with the content locations that are included in the ad campaign. In some instances, the advertiser can pay the owners of the content locations or an advertising system for each such ad presentation (i.e., ad placement) Advertisers also may select content locations to include in an ad campaign so as to reach potential viewers that are more likely to be interested in products sold by the advertisers. For example, an advertiser may rely on targeting information, such as demographic information of potential viewers, when selecting content locations to include in an ad campaign.